Cart Wheel Assembly with Replaceable Tire

ABSTRACT

The disclosure addresses a series of interactions between wheel rims and a number of different replaceable tire segments to cover the wheel rims. The disclosure teaches more than one way to engage the one or more tire segments to wheel rims and to form seams between ends of the one or more tire segments. The tire segments may be removed and replaced so that the wheel rim and wheel bearing may be used longer than the useful life of the tire segments.

This application claims priority to and incorporates by referenceco-pending and commonly assigned Patent Cooperation Treaty PatentApplication No. PCT/US18/43981 filed Jul. 26, 2018 for Cart WheelAssembly with Replaceable Tire. This application claims through the '981application the benefit of U.S. Provisional Application No. 62/537,403filed Jul. 26, 2017 for Shopping Cart Wheel Assembly with ReplaceableTire.

BACKGROUND Field of the Disclosure

This disclosure relates generally to wheels including wheels for carts,including shopping carts of all types that are used by customers inretail stores. The teachings of the disclosure may be applied to otherwheels using non-pneumatic tires.

Related Art

FIG. 1 introduces a wheel from a shopping cart. The wheel assembly 100is connected to a caster assembly 130 by a nut 138 and bolt 134 wherethe bolt 134 runs through the center of a hub and bearing assembly 120.The wheel assembly 100 includes a rim 144 and a tire 140 that rotaterelative to the bolt 134 as there is a bearing (not shown) that allowsfor this relative motion. Frequently there is a sleeve bearing as thattype of bearing is of lesser cost than a ball bearing.

There are many different shopping carts used in various retailenvironments. Many carts have a wire basket for the receipt of goods.Some carts such as those used in hardware stores or bulk item storessuch as a Costco® store are large flat carts. There are other morespecialized carts, particularly in hardware stores, that are adapted forreceipt of lumber, drywall, or other common construction items. Manystores have carts that include places for children to sit includingcarts that have been made to resemble vehicles or other shapes to amusethe child occupants.

Shopping carts of the wire basket type vary considerably in the size andexpected loading. Some carts used in clothing stores or a pharmacy arerelatively small in order to get through small aisle cross sections andaround displays. These smaller carts typically have lower expectationsfor loading. Grocery store carts are very common and have largercapacities and loading expectations. There are still larger basket typecarts for warehouse stores that sell larger items or items in bulk.

Carts typically have at least some caster assemblies 130 with a bearing136 to allow for rotation of the wheel assembly 100 to allow for achange of direction of the cart. Some carts have two wheel assembliesthat are not free to change direction and two wheel assemblies that arefree to change direction. Other carts have all wheel assemblies capableof changing direction.

Problem with Prior Art Solutions

Unlike a cart used by employees in an industrial setting, stores place apremium on having a “quiet ride” for their retail carts. They do notwant customers to be annoyed by the noise and vibration of a wheelassembly on a cart the customer is pushing or to hear the noise from awheel assembly on a cart nearby that is being pushed by anothercustomer.

One way to provide for a quiet ride is to choose a relatively softmaterial for the tire. Prior art tires for shopping cart wheelassemblies were frequently made from thermoplastic polyurethane (TPU).Per Wikipedia (https://en.wikipedia.org/wiki/Thermoplasticpolyurethane),TPU has properties that make it a reasonable choice for this use as TPUhas elasticity and resistance to oil, grease, and abrasion. TPU is amixture of hard and soft segments in a block copolymer and thus can betuned to a particular desired hardness.

Eventually the TPU tire becomes imperfect and becomes annoying toshoppers. The defect may be a flat spot or a gouge where there is now adiscontinuity in the tire surface. Either way, the rotation of the tirewill produce a sound and vibration each time the flat spot or gougerotates to come in contact with the floor.

One estimate of the useful life of a shopping cart tire is only twoyears. Due to the way the prior art tires were attached to the prior artrims, the entire wheel assembly 100 including: tire 140, rim 144, andthe hub and bearing assembly 120 were discarded. This discard all designleads to a preference for using the least expensive bearing as it is adisposable part. The aggregate disposal of wheel assemblies 100 addsgreatly to the volume of material in landfills. Disposing of theundamaged rim 144 and the undamaged hub and bearing assembly 120 becauseof the early failure of the tire is unfortunate and raises the cost ofoperation of shopping carts. Given that there are millions of shoppingcarts in just the United States, the volume of discarded wheelassemblies 100 from carts is massive.

Loading Constraints.

There are three main loading conditions for the tire 140 (See FIG. 1).The first is the vertical load that tends to flatten the tire. Thesecond is the rolling direction load that is minimized as long as thehub and bearing assembly 120 are not seized and wheel assembly 100 isallowed to roll. The third loading direction is the side load conditionand is the one that is most important to the design. The following is adescription of how this side load impacts the design. This descriptionstarts with an examination of the robust, but non replaceable tiredesign of the prior art to highlight the challenge of creating areplaceable tire that will perform as well as the non-replaceable priorart tire 140.

First Example

FIG. 2 shows a perspective view of a tire 140 that lies on a rim 144.FIG. 3 shows a cross section of the tire 140 and rim 144 showing thesimple arrangement of the tire 140 along the perimeter of the rim 144.

Response to Lateral Force.

FIG. 4 shows a cross section of the lower portion of the tire 140 andrim 144 from FIG. 2 and FIG. 3. If someone drove one shopping cart intothe side of another shopping cart, the struck cart would have a lateralforce 184 to move the cart and the attached rim sideways. The portion ofthe tire 140 in contact with the ground 188 would resist moving sidewaysbecause of the friction force 180 and the tire 140 may be separated fromthe rim 144. The problem is particularly acute for a wheel assembly 100that is not able to change orientation with respect to the cart which isfrequently true for two of the four wheel assemblies.

More specifically, if the tire 140 is experiencing a vertical normalforce (N) due to the weight of a cart and the contents of the cart,there will be a friction force (F_(f)) 180 that is proportional to thenormal force and the coefficient of friction between the tire 140 andthe ground (u). The relationship can be expressed as F_(f)=N*u. Thecombination of the Applied Load (F_(A)) (lateral force 184) on the rim144 and the equal and opposite friction force F_(f) 180 will tend tomake the tire 140 separate from the rim 144.

The sideward force may not come from a cart collision. It could comefrom a user trying to slide the cart sideways to change directions intight quarters. Or the sideways force may come when a store employee ismoving a long train of shopping carts back into the store and needs tomove the end of the train of carts closest to the employee sideways toallow the train of carts to navigate back into the store. Thus, rim 144will experience lateral forces with some frequency, even if the cart isnot hit in the side by another cart.

A Second Example

FIG. 5 shows a cross section of a portion of a rim 144 and tire 140 witha first order solution to make the tire 140 less likely to be separatedfrom the rim 144. The wheel rim 144 has added geometry to the rim 144which is a rim center ridge 148. The tire 140 will have a mating grooveto receive the rim center ridge 148.

In FIG. 6 the lateral force 184 is applied to the rim 144 through thecart (not shown here). A reaction to the ground 188 provides a frictionforce 180 which tends to cause the tire 140 to separate from the rim144.

The rim center ridge 148 prevents the tire 140 from sliding off asdiscussed in connection with FIG. 4. However, due to the way the tire140 deforms as it drags on the ground as the cart moves laterally, thetire 140 on the opposite side of the lateral force 184 will separatefrom the rim 144. This may be called roll-out separation. Given adequatelateral force 184 and coefficient of friction between the tire 140 andthe ground (u), the roll-out separation may be severe enough to pull thetire 140 so that it does not reseat when the application of lateralforce stops.

FIG. 7 shows a rim 144 and tire 140 with a more complex rim center ridge148. However, even the rim 144 and tire 140 may suffer from roll-outseparation under severe lateral forces.

Through Openings.

FIG. 8 shows a front view of a rim 144 with a prior art solution to thisproblem. In addition to the more complex rim center ridge 148 (See FIG.9), the rim 144 has a series of through holes 146. A tire 140 can bemolded onto the rim 144 so that the tire material passes through thethrough holes 146 in the rim 144 and thus engages the tire 140 to therim 144 so that the tire 140 is not peeled off during incidents ofsignificant lateral forces on the wheel assembly 100.

FIG. 9 shows cross section in perspective view that shows a rim 144 withengaged tire 140 that extends through the through holes 146 in the rim144. Tires 140 that have material that passes through openings in therim 144 are the current prior art solution to creating durable wheelassemblies for carts as shown in FIG. 1 discussed above. However, thiswheel assembly 100 design requires the tire material to be molded inplace on the rim so that the tire material can pass through the throughholes 146 in the rim 144. This molding process can only be effectivelyaccomplished at a manufacturer's facility and is not an option forproviding replacement tires.

Vocabulary

Unless explicit to the contrary, the word “or” should be interpreted asan inclusive or rather than an exclusive or. Thus, the default meaningof or should be the same as the more awkward and/or.

Unless explicit to the contrary, the word “set” should be interpreted asa group of one or more items.

Within this disclosure the terms radially outward or radially inwardshould be interpreted as moving in a way that increases or decreases thedistance to the center of the rim or other relevant object. Is notnecessary that the movement be precisely aligned with a particularradius of the rim as long as one of skill in the art would be able todiscern whether the motion was largely moving towards or away from thecenter of the object.

Frequently, when describing an industrial process it is useful to notethat a given parameter is substantially met. Examples may besubstantially parallel, substantially perpendicular, substantiallyuniform, and substantially flat. In this context, substantially X meansthat for purposes of this industrial process it is X. So something thatmay not be absolutely parallel but is for all practical purposesparallel is substantially parallel. Likewise, mixed air that hassubstantially uniform temperature would have temperature deviations thatwere inconsequential for that industrial process.

As recognized in C. E. Equipment Co. v. United States, 13 U.S.P.Q.2d1363, 1368 (Cl. Ct. 1989), the word “substantially” in patent claimsgives rise to some definitional leeway—thus the word “substantially” mayprevent avoidance of infringement by minor changes that do not affectthe results sought to be accomplished.

SUMMARY OF THE DISCLOSURE

Some of the aspects of the teachings of the present disclosure may besummarized as a method of applying a tire to a rim. The method includingforming a tire seam with:

a first seam end having at least one locking finger that extends beyonda first seam face, the first seam end having a first seam end firstsidewall and a first seam end second sidewall that cover a least aportion of a center ridge that extends along at least a portion of acircumference of the rim; and

a second seam end having at least one opening to receive a lockingfinger behind a second seam face, the second seam end having a secondseam end first sidewall and a second seam end second sidewall that covera least a portion of the center ridge that extends along at least aportion of the circumference of the rim.

The method including inserting the at least one locking finger into theat least one opening to draw the first seam face to the second seamface; and after inserting the at least one locking finger into the atleast one opening to draw the first seam face to the second seam face,inserting a finger locking pin to engage a passageway in the second seamend first sidewall, a passageway in the second seam end second sidewall,a passageway through a portion of the locking finger, and at least onepassageway through the rim.

A variation on this teaching is to use a finger locking pin but notengage the rim with the finger locking pin.

Some of the aspects of the teachings of the present disclosure may besummarized as a method of disengaging a seam at a joint between two tireends for a tire covering a rim. The method includes pressing on a firstend of a first locking pin at a first tire sidewall to force a secondend of the first locking pin to extend outward from a second tiresidewall, then removing the first locking pin from engagement with a rimso that a second seam end is no longer engaged with the rim by the firstlocking pin; and disengaging a locking finger extending from a firstseam end from an opening in the second seam end such that the first seamend is disengaged from the second seam end.

Some of the aspects of the teachings of the present disclosure may besummarized as a creating an assembly made from a rim with a tire on therim. The rim having a set of locking grooves to receive locking ribsfrom a tire segment. The tire segment with a first end and a second end,the first end and the second end adapted to form a tire seam. The tiresegment having a spacing of a pair of locking ribs on the tire segmentrelative to a spacing of a pair of locking grooves on the rim causing aportion of the tire segment to become elongated in order to place afirst locking rib in a first locking groove and second locking rib in asecond locking groove adjacent to the first locking groove.

Some of the aspects of the teachings of the present disclosure may besummarized as a method of applying a tire segment to a rim by placing atire segment around at least a portion of a rim such that sidewalls ofthe tire segment cover at least a portion of a center ridge on at leasta portion of the portion of the rim. The method includes placing atleast a portion of a tire joint section of a second type over at least aportion of a tire joint section of a first type to form an overlappedjoint and engaging at least one passageway through the rim so that theoverlapping joint is bound to the rim.

Other aspects of the teachings contained within this disclosure areaddressed in the claims submitted with this application upon filing.Rather than adding redundant restatements of the contents of the claims,these claims should be considered incorporated by reference into thissummary.

This summary is meant to provide an introduction to the concepts thatare disclosed within the specification without being an exhaustive listof the many teachings and variations upon those teachings that areprovided in the extended discussion within this disclosure. Thus, thecontents of this summary should not be used to limit the scope of theclaims that follow.

Inventive concepts are illustrated in a series of examples, someexamples showing more than one inventive concept. Individual inventiveconcepts can be implemented without implementing all details provided ina particular example. It is not necessary to provide examples of everypossible combination of the inventive concepts provide below as one ofskill in the art will recognize that inventive concepts illustrated invarious examples can be combined together in order to address a specificapplication.

Other systems, methods, features and advantages of the disclosedteachings will be immediately apparent or will become apparent to onewith skill in the art upon examination of the following figures anddetailed description. It is intended that all such additional systems,methods, features and advantages be included within the scope of and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure can be better understood with reference to the followingfigures. The components in the figures are not necessarily to scale,emphasis instead being placed upon illustrating the principles of thedisclosure. Moreover, in the figures, like reference numerals designatecorresponding parts throughout the different views.

FIG. 1 introduces a wheel from a shopping cart.

FIG. 2 shows a perspective view of a tire 140 that lies on a rim 144

FIG. 3 shows a cross section of the tire 140 and rim 144 showing thesimple arrangement of the tire 140 along the perimeter of the rim 144.

FIG. 4 shows a cross section of the lower portion of the tire 140 andrim 144 from FIG. 2 and FIG. 3.

FIG. 5 shows a cross section of a portion of a rim 144 and tire 140 witha first order solution to make the tire 140 less likely to be separatedfrom the rim 144.

FIG. 6 shows the lateral force 184 is applied to the rim 144 through thecart

FIG. 7 shows a rim 144 and tire 140 with a more complex rim center ridge148.

FIG. 8 shows a front view of a rim 144 with a prior art solution to thisproblem.

FIG. 9 shows cross section in perspective view that shows a rim 144 withengaged tire 140 that extends through the through holes 146 in the rim144.

FIG. 10 shows a side view of a half-rivet 250.

FIG. 11 shows a perspective view showing the outward surface 270 of onehalf-rivet 252 and the flat inside face 274 of the half-rivet 254 on theopposite side of the rim

FIG. 12 shows cross section of a tire 240 mounted on rim 300.

FIG. 13 introduces a T-tongue part of the tire joint.

FIG. 14 shows a groove end 450 of a segment of a tire 240 that can matewith the T-tongue 400 of FIG. 13.

FIG. 15 shows a shopping cart 110 resting with the handle 112 up.

FIG. 16 shows a portion of the shopping cart 110 and wheel assembly 118.

FIG. 17 shows a rim 300 receiving a single piece tire segment 490 with aT-tongue 400 and a groove end 450.

FIG. 18 shows a rim 300 with a first tire segment 494 having a T-tongue400 and a groove end 450.

FIG. 19 shows a second tire segment 498 having a T-tongue 400 and agroove end 450.

FIG. 20 shows the rim 300 after the T-tongue 400 of second tire segment498 is placed on the rim 300 to place the T-riser section 320 betweentwo rivet holes 308.

FIG. 21 shows the first tire segment 494 and second tire segment 498with a pair of seams 440.

FIG. 22 shows the inner side of a tire segment 492.

FIG. 23 shows a front view of a rim 500.

FIG. 24 shows a front-top-left side perspective view of the rim 500 fromFIG. 23.

FIG. 25 is a top-front perspective view of a portion of rim 500 whichshows joint portion 550 of the rim with joint groove 532 and an enlargedview of the male pin bore 520 and first locking pin bore 524 and secondlocking pin bore 528

FIG. 26 shows a front view of tire 600.

FIG. 27 shows a front-top-left side perspective view of the tire 600from FIG. 26.

FIG. 28 provides an upward-front perspective view looking up into themale portion 630 of tire 600.

FIG. 30 provides an upward-front perspective view looking up into thefemale portion 660 of tire 600.

FIG. 31 provides a downward-front perspective view looking onto the topsurface of the female portion 660 of tire 600.

FIG. 32 shows a top-front perspective view of a portion of rim 500 andtire 600. From this view, one can see the female portion 660 seated onthe rim 500.

FIG. 33 shows a front-right-top perspective view of a portion of rim 500and tire 600.

FIG. 34 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 33 but with the locking finger 640 ofthe male portion 630 beginning to engage with opening 668 in the femaleportion 660.

FIG. 35 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 34 but with the locking finger 640 ofthe male portion 630 almost seated in opening 668 in the female portion660.

FIG. 36 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 35 but with the locking finger 640 ofthe male portion 630 fully seated in opening 668 in the female portion660.

FIG. 37 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 36 but with the male locking pin 730fully inserted into the first sidewall bore 734 and through the secondsidewall bore 738 after passing through the male pin bore 520 in rim 500to hold the male portion 630 to the rim 500.

FIG. 38 is a front view of rim 500 with specifics on the spacing of thelocking grooves 512.

FIG. 39 shows a front view of tire 600 before engagement with the rim500.

FIG. 40, FIG. 41, FIG. 42, and FIG. 43 each show a side view of apartial rim and a partial tire to show some locking groove/locking ribcombinations.

FIG. 44 shows that the first step is to remove the locking pins 730 and760.

FIG. 45 illustrates the insertion of a distal end 594 of a tool 590 suchas an appropriate size flathead screwdriver into the seam 620 betweenthe male portion 630 and the female portion 660 of the tire 600.

FIG. 46 illustrates a continuation of the process as the distal end 594of the tool 590 is moved between the locking finger 640 and the secondsidewall 608. The process may continue for several iterations until thelocking finger 640 is out of the opening 668 in the female portion 660.

FIG. 47 shows a tire 900 made from a short segment 910 with a pair ofmale portions 630 with locking fingers 640, one at a first end 914 andone at a second end 918.

FIG. 48 is a front-top perspective view of a portion of a tire 930 witha male portion 934 with a pair of locking fingers 640.

DETAILED DESCRIPTION

An improved wheel assembly for use in shopping carts would have a tirethat is a replaceable part. Desirable characteristics include:

-   -   Tire is installable while wheel rim is connected to the cart        frame or caster assembly.    -   Tire is able to be removed easily while on cart frame or caster        assembly.    -   Tire must be secure enough while on rim to withstand routine        operational loads.    -   Tire is ideally manufacturable with mass production tooling.    -   Removed tire material is ideally able to be directly recycled        (i.e. does not contain metal non-removable pins, clips, or other        materials that would prevent direct meltdown of tire).    -   Design may optionally use special tools to aid in tire        installation and or tire removal, but it is beneficial to have        an option for removal and installation with standard tools (such        as a utility knife, screwdriver, pliers, et cetera) to avoid the        absolute requirement of having the special tools available.

Half Rivets to Preclude Roll-Out Separation.

As noted above, the prior art solution of molding a tire to the rim tocause the tire material to capture the rim by flowing through holes inthe rim prevents roll-out separation but at the cost of precludingreplacement of the tires.

One solution that allows removable tires that engage the rim to avoidroll-out separation uses push-in half-rivets. FIG. 10 shows a side viewof a half-rivet 250. FIG. 11 shows a perspective view showing theoutward surface 270 of one half-rivet 252 and the flat inside face 274of the half-rivet 254 on the opposite side of the rim (rim not shownhere).

The half-rivet 250 may be simply a shaft 260 with an expanded diametersection (head 262) on top. The head 262 may be frustoconical with aleading portion 266, a tapered portion 264 and a trailing flange 268. Asthis is a half-rivet, approximately half of the rivet is missing andthere is the flat inside face 274. One of skill in the art willappreciate that the inside face does not have to be flat as long as itfits within the rivet through a hole in the rim and has room relative tothe radial face of the rim.

If the head 262 of the push-in half-rivet 250 is pressed into apassageway in the rim of similar size and shape to the shaft 260 of thehalf-rivet 250, the expanded diameter of head 262 will compress to fitin the passageway and will snap back out laterally when the trailingflange 268 of the half-rivet head 262 exits the passageway. Since theexpanded diameter of the half-rivet head has a barbed shape with atrailing flange 268, the half-rivet head 262 will resist being pulledback out of the passageway.

FIG. 12 shows cross section of a tire 240 mounted on rim 300. The huband bearing assembly (compare 120 in FIG. 1) is not shown in this crosssection but there is a center sleeve 304 to receive the hub and bearingassembly.

In this example, there are four pairs of half-rivets that secure thetire 240 to the rim 300. The cross section shown in FIG. 12 runs throughhalf-rivet 252 and half-rivet 254 at 6 o'clock on the rim 300. The crosssection also runs through half-rivet 220 and half-rivet 224 at 12o'clock on the rim 300. In FIG. 12, the half-rivet 290 is visible at 3o'clock on the rim 300 but the half-rivet on the back side of the rim300 is not. The other half of the rim 300 would have a set ofhalf-rivets at 9 o'clock on the rim 300 and the other halves ofhalf-rivets 250, 254, 220, and 224. Those of skill in the art willappreciate that each half-rivet passes through a rivet hole 308 in therim 300.

Those of skill in the art will appreciate that the number of pairs ofhalf-rivets does not need to be four. It is possible that it could beless than four but could easily be more than four pairs.

Those of skill in the art will appreciate that the half-rivets could bearranged so that they do not align across the rim. Thus on one face ofthe rim, the half-rivets could be placed at 12, 3, 6 and 9 o'clock andon the opposite face of the rim the half-rivets could be placed at 1, 3,5, 7, 9, and 11 o'clock. Note in this example, the number of half-halfrivets on the first side of the rim is not equal to the number ofhalf-rivets on the other side of the rim. However while many variationsare possible, it is likely that the half-rivets will be arranged inpairs on either side of the rim 300 as shown in FIG. 12.

Tire Joint.

The proposed design uses at least one tire segment. Each place that twotire segment ends meet, there is a seam. Minimizing the discontinuity atthe seams is important to avoid having the seams provide a source fornoise or vibration as the tires on the wheels are rolled across verysmooth floors. Note that rolling across a rough surface such as asphaltis actually less demanding from a performance perspective as customerswill expect vibration on the rough surface. The customers will belargely intolerant of noise or vibration coming from the wheelassemblies when rolling the cart wheel assemblies on extremely smoothfloors—as are found in many retail establishments.

The seam problems can be divided into peel-up and gapping. Peel-up iswhen an end of the tire segment peels up away from the rim. Gapping iswhen the two tire segments do not peel up, but a noticeable gap appearsbetween the two adjacent tire segments.

T-Tongue End.

FIG. 13 introduces one part of the tire joint. Unlike the tire of theprior art that was molded on the rim, the present disclosure teaches atire 240 that is created away from the rim 300 and then applied to therim 300. The joint has two components, a T-tongue 400 shown in FIG. 13and a groove end 450 discussed in connection with FIG. 14.

FIG. 13 shows a T-tongue 400 with a tongue height 404 that is less thanthe tire height 408. The T-tongue 400 extending beyond the main portion412 of the tire 240 forms a T to rest on top of the center ridge 348 ofthe rim 300.

The components of the T-tongue 400 extend from the tongue base 416outward with a T-riser section 420 that covers the rim center ridge anda wider T-crossbar 424 that extends outward perpendicular to the rimcircumference. The T-tongue 400 has three planes perpendicular to thecircumference of the rim:

1) tongue base 416;

2) T-proximal flange 428 on the side of the T-crossbar 424 facing thetongue base 416; and

3) the T-distal flange 432 on the opposite side of the T-crossbar 424.

Groove End.

FIG. 14 shows a groove end 450 of a segment of a tire 240 that can matewith the T-tongue 400 of FIG. 13. The groove end 450 is adapted to coverthe T-tongue 400 and then hold the pair of segment ends (400 and 450)down on the rim (FIG. 13 300) with a pair of half-rivets 454 and 458that extend through corresponding passageways in the rim 300. The grooveend 450 has three planes perpendicular to the circumference of the rim:

1) distal groove flange 456 shaped to be placed adjacent to the tonguebase 416;

2) medial groove flange 478 shaped to be placed adjacent to T-proximalflange 428 on the side of the T-crossbar 424 facing the tongue base 416;and

3) proximal groove flange 482 shaped to be adjacent to the T-distalflange 432 on the opposite side of the T-crossbar 424.

One of skill in the art will appreciate that by careful selection of thelength of the T-riser section 420 that one could trap the T-crossbar 424in the groove end 450 of a segment between the medial groove flange 478and the proximal groove flange 482 so that the T-riser section 420 is inelastic deformation and thus in tension and pulls the distal grooveflange 456 towards the tongue base 416 to minimize any gap between thetwo tire segment ends (400 and 450). The pair of half-rivets (454 and458) inserted through rivet holes 308 in the rim 300 prevents the grooveend 450 of the one segment and the entrapped T-tongue segment 400 frompeel-up.

Installation Process.

The installation process can use one or more tire segments. In order tofocus on the rim and the tire segments, other components such as the huband bearing assembly or the engagement of the wheel assembly to a cartcaster or to a fixed portion of the cart frame are not included in theassembly images.

One of skill in the art will appreciate that as each seam uses a pair ofhalf-rivets to help hold the seam, a wheel and tire assembly havingthree or more segments would have additional passageways in the rim forreceipt of additional half-rivets at the seams and possibly additionalhalf-rivets at the midpoints between adjacent seams. In an extreme casewith many short tire segments, it may be possible to not have a set ofhalf-rivets placed between adjacent seams as the short arcs betweenadjacent seams may make those half-rivets unnecessary. Conversely, whenthere are only one or a few tire segments on a large cart wheelassembly, it may be desirable to have more than one pair of half-rivetsengage the tire segment to the rim as shown above in the one tiresegment example.

Installation Process—One Tire Segment.

FIG. 15 shows a shopping cart 110 resting with the handle 112 up. Theshopping cart 110 may have two wheel assemblies 114 and 116 at the frontend of the shopping cart 110 which may turn to allow the cart to besteered. The shopping cart 110 may have two more wheel assemblies 118and 124 at the back end and not able to rotate to steer the shoppingcart 110. Wheel assemblies 118 and 124 do not have tires installed yet.

FIG. 16 shows a portion of the shopping cart 110 and wheel assembly 118.Notice that there are a set of through bores 312 in rim 300. A distalend of a tool 460, such as a Phillips head screwdriver, may be insertedthrough a hole 464 in the shopping cart 110 shopping cart and throughone of the through bores 312 to stop the ability of the rim 300 torotate around the hub and bearing assembly 120 located in the centersleeve 304 in the rim 300. The use of through bores 312 to immobilizethe rim 300 is optional and thus the presence of the through bores 312in the rim 300 is optional.

FIG. 17 shows a rim 300 receiving a single piece tire segment 490 with aT-tongue 400 as discussed in FIG. 13 and a groove end 450 as discussedin FIG. 14. To allow a focus on the interaction of the single piece tiresegment 490 with the rim 300, no other components are shown in FIG. 17.

One can observe from FIG. 17 that the process is to place the T-risersection 420 between two rivet holes 308. The single piece tire segment490 is then applied around the circumference of the rim 300 with thecenter ridge 348 enveloped by the single piece tire segment 490. Thehalf-rivets 250 are inserted through the rivet holes 308 and retained,with the half-rivets 454 and 458 inserted last to complete theinstallation.

With appropriate spacing of the half rivets and rivet holes 308, thesingle piece tire segment 490 could be installed clockwise orcounterclockwise on rim 300 as it is the pairs of half-rivets thatengage with the rim 300 not the T-tongue 400 or the groove end 450.

Returning to FIG. 16, one of skill in the art will appreciate that thetool 460 may be removed from the hole 464 and removed from the throughbore 312 and the rim 300 rotated to allow the user performinginstallation of the single piece tire segment 490 to position the nextset of rivet holes 308 to be engaged with half-rivets to be unobstructedby any portion of the shopping cart 110. After repositioning, the tool460 may be inserted through the hole 464 and an appropriately locatedthrough bore 312 so that the rim is not able to rotate around the huband bearing assembly 120.

Installation Process—More Than One Tire Segments.

FIG. 18 shows a rim 300 with a first tire segment 494 having a T-tongue400 and a groove end 450. As was done above, the T-riser section 420 isplaced between two rivet holes 308. The first tire segment 494 is thenapplied around the circumference of the rim 300 with the center ridge348 enveloped by the first tire segment 494. The half-rivets 250 areinserted through the rivet holes 308 and retained. Note that thehalf-rivets 454 and 458 from the groove end 450 are not immediatelyinserted as these will be inserted last to complete the installation.

FIG. 19 shows a second tire segment 498 having a T-tongue 400 and agroove end 450. FIG. 19 differs from FIG. 18 in that groove end 450 ofsecond tire segment 498 is put into position with the insertion ofhalf-rivets 454 and 458 (458 not visible here) to capture the T-tongue400 of first tire segment 494. The remainder of second tire segment 498can be inserted over the center ridge 348 of the rim 300. Note that thesecond tire segment 498 is sufficiently pliable that it can be bentduring the placement process as indicated by inflection point 486.

FIG. 20 shows the rim 300 after the T-tongue 400 of second tire segment498 is placed on the rim 300 to place the T-riser section 320 betweentwo rivet holes 308. The groove end 450 of the first tire segment 494was not engaged with the rim when the first tire segment 494 was appliedbut is now ready to lock down the T-tongue 400 of the second tiresegment 398. Note that first tire segment 494 is sufficiently pliable toallow the groove end 450 to be lifted away from the rim 300 whileportions of the first tire segment 494 are engaged with the rim 300through inserted half-rivets 252.

FIG. 21 shows the first tire segment 494 and second tire segment 498with a pair of seams 440. At seam 440, the groove end 450 of the secondtire segment 498 holds down the T-tongue 400 of the first tire segment494. At second seam 440, the groove end 450 of the first tire segment494 holds down the T-tongue 400 of the second tire segment 498.

One of skill in the art will recognize that the connection of oneT-tongue 400 and one groove end 450 of the tire segments could beaugmented by the use an adhesive such as Liquid Nails® brandconstruction adhesives. A small amount of adhesive could be placed onthe T-tongue 400 for example to bind the top of the T-tongue 400 to theinside of the groove end 450. The adhesive will not impair thesubsequent removal of the tire after end of service as the removalprocess does not work to undo the joining of the two tire segment endsand the adhesive is placed between tire segments ends 400 and 450 andnot between the tire segment (490, or 494 and 498) and the rim 300.

Tire Removal.

The removal of the one or more tire segments may begin in the samemanner as discussed above for tire installation. The shopping cart 110may be positioned so that the wheel assembly to have the tire removed isaccessible (See FIG. 15). A tool 460 may be inserted through a hole 464in the shopping cart 110 and through one of the through bores 312 tostop the ability of the rim 300 to rotate around the hub and bearingassembly 120 located in the center sleeve 304 in the rim 300 (See FIG.16).

The tire removal process works the same for tires made from one tiresegment 490 or from more than one segment such as first tire segment 494and second tire segment 498.

The set of half-rivet heads 262 of the half-rivets 250 may be cut byinserting a sharp edge 468 (represented here by a utility knife blade)between the flange 268 (See FIG. 10) of the half-rivet 250 and the rim300 in order to remove the half-rivet heads 262 of the half-rivets 250from the shaft 260. Without the flange 268, the shaft 260 is no longerretained by the rim 300. The order of cutting the half-rivets 250 is notimportant.

Use of Adhesive and Impact on Tire Removal.

One of skill in the art will recognize that the connection of oneT-tongue 400 and one groove end 450 of the tire segments could beaugmented by the use of an adhesive such as Liquid Nails® brandconstruction adhesives. A small amount of adhesive could be placed onthe T-tongue 400 for example to bind the top of the T-tongue 400 to theinside of the groove end 450. The adhesive will not preclude thesubsequent removal of the tire after end of service as the removalprocess does not work to undo the joining of the two tire segment endsand the adhesive is placed between tire segments ends 400 and 450 andnot between the tire segment (490, or 494 and 498) and the rim 300.

If an adhesive has been used to adhere a T-tongue 400 to one groove end450 then in addition to removal of half-rivet heads 262, at least onecut can be made to at least one tire segment. Turning to FIG. 18, onecan see that the rim 300 has a number of transverse notches 350 in therim center ridge 348. The location of the transverse notches 350 may benoted by notch indicators 354 on the outsides of the rim 300, such asthe arrowheads used here. The transverse notch 350 allows the sharp edge468 to cut through the tire segment (490 or 494 and 498) from one sideto the other without having to cut around the raised perimeter of therim center ridge 348.

As shown in FIG. 22 showing the inner side of a tire segment 492, thetire segment 492 may have a transverse ridge 488 that corresponds to theupper portion of the transverse notches 350 but does not have sufficientheight to extend to the bottom of the transverse notches 350 in the rim300 in order to facilitate cutting the entirety of the transverse ridge488 to free the tire segment 492 from the rim 300.

This wedge shaped transverse ridge 488 would resist any tendency of thetire segment 492 to sag into the transverse notches 350 when thetransverse notches 350 is the portion of the tire segment 492 supportingthe wheel assembly 100. One of skill in the art could have the wedgeshaped transverse ridge 488 that completely fills the transverse notches350 but any debris left in the transverse notches 350 duringinstallation or manufacturing tolerance excursions could lead to aslight raised portion of the tire segment 492 above a transverse notch350 and cause a slight vibration. Thus, a wedge shaped transverse ridge488 that does not extend to the bottom of the transverse notch 350 ispreferred.

While the wheel rim 300 may have several transverse notches 350, onlyone cut across the tire segment 492 would be required to remove the tiremade from one or more segments with adhesive bonded seams from the wheelrim 300.

One of skill in the art will appreciate that one could cut the tire at atransverse notch 350 before cutting off any or all of the first and thencut off the heads 262 of the half-rivets 250. The order of the two setsof actions to remove a tire from a rim 300 is not limited to a specificsequence.

ALTERNATIVES AND VARIATIONS

Segments with Uniform Ends.

One of skill in the art will appreciate that when using an even numberof tire segments 494 and 498 instead of having a tire segment with oneend having a T-tongue 400 and one groove end 450 as shown above, thatone could have one tire segment with both ends as T-tongues 400 thatmate with a tire segment with two groove ends 450. Depending on thedesign, this may require a change in the spacing of passageways in therim to receive the half-rivets, but this adjustment would be withinreach of one of skill in the art. One of skill in the art willappreciate that there is some advantage for a manufacturing processwhere each segment is the same as every other segment as this reducesthe needs for different molds and inventory requirements to storedifferent types of segments.

Pre-Loaded Half-Rivets.

Those of skill in the art will appreciate the benefit of havinghalf-rivets 250 (See FIG. 22) that are under tension to pull the tiresegment (or segment ends at a seam between two ends) towards the rim300. A design choice available to increase tension is to size theun-stretched shaft 260 of the half-rivets slightly shorter than thepassageway length of the rivet holes 308 through the rim 300. When thehalf-rivet head 262 is pressed through a rivet hole 308 in the rim 300to allow the trailing flange 268 to extend out of the rivet hole 308 thedistance between the trailing flange 268 and the tire end of the shaft260 will be more than the un-stretched length of the shaft 260 of thehalf-rivet 250. This stretching of the shaft 260 is at least partiallyelastic deformation which acts as a stretched spring to hold the tiresegment (490, 494, and 498) to the rim 300.

One of skill in the art will appreciate that pushing the trailing flange268 of half-rivet 250 sufficiently to stretch the half-rivet shaft 260may require a tool to focus force on the pushing of half-rivet head 262through the rivet hole 308 in the rim 300 by pushing upon the tiresegment above the rivet hole 308.

Other Rivet Choices.

Those of skill in the art will appreciate that other rivet shapes couldbe used instead of the half-rivets 250 used in this disclosure.

Reductions in Rim Center Ridge Height at Seams.

Optionally, the portion of the center ridge 348 intended to be coveredby the T-tongue 400 may be made less tall so that the T-tongue 400 orpossibly the thickness of the groove end 450 positioned above theT-tongue 400 (or both) may be made slightly thicker to increase thestrength or durability of these segment ends.

Joints with Locking Pins.

The first four figures introduce components on the rim 500 and tire 600.The interactions with these components will be addressed in specializedfigures to follow.

Rim 500.

FIG. 23 shows a front view of a rim 500. Rim 500 has some of thefeatures previously presented with respect to rim 300. For example, rim500 has the optional through bores 516 to use with a tool 460 engagedwith a hole 464 (See FIG. 16) to stop the ability of the rim 500 torotate around the hub and bearing assembly 120 (See FIG. 1).

FIG. 24 shows a front-top-left side perspective view of the rim 500 fromFIG. 23. FIG. 23 shows center ridge 548 of rim 500. FIG. 23 and FIG. 24show male pin bore 520 and first locking pin bore 524 and second lockingpin bore 528. These pin bores will be discussed in detail below. FIG. 23and FIG. 24 show a series of locking grooves 512 and a joint groove 532.

FIG. 25 is a top-front perspective view of a portion of rim 500 whichshows joint portion 550 of the rim with joint groove 532 and an enlargedview of the male pin bore 520 and first locking pin bore 524 and secondlocking pin bore 528. The joint portion 550 includes a finger gap 554which will be described below.

Tire 600.

FIG. 26 shows a front view of tire 600. FIG. 27 shows a front-top-leftside perspective view of the tire 600 from FIG. 26. The tire 600 has amale portion 630 and a female portion 660 that are joined to form a seambetween the male portion 630 and female portion 660. The tire 600 has aset of locking ribs 612 for placement in the locking grooves 512 in therim 500. Visible in FIG. 27 are a first sidewall 604 and a secondsidewall 608 that cover the sides of the center ridge 548 of the rim500. Components important to forming a joint between the male portion630 and the female portion 660 are visible in FIG. 26 and FIG. 27 butthese components are best introduced by enlarged sections discussedbelow.

Male Portion 630.

FIG. 28 provides an upward-front perspective view looking up into themale portion 630 of tire 600. FIG. 29 provides a downward-frontperspective view looking onto the top surface of the male portion 630 oftire 600.

Female Portion 660.

FIG. 30 provides an upward-front perspective view looking up into thefemale portion 660 of tire 600. FIG. 31 provides a downward-frontperspective view looking onto the top surface of the female portion 660of tire 600.

Joint Components.

Visible in FIG. 28 and FIG. 29 is locking finger 640 which has: anoutward portion 644, a gap 646, and a downward portion 648. The gap 646separates the joint rib 632 that fits in the joint groove 532 of rim 500from the downward portion 648 of the locking finger 640. Having agenerous gap 646 by placing the joint rib 632 a generous distance awayfrom the face 658 of the male portion 630 affords some leeway whenstretching locking finger 640 so that the male portion 630 does not makecontact with the female portion 660 and interfere with the insertion ofthe locking finger 640 into the opening 668. The distance that face 658extends outward from 632 can be adjusted so that after insertion face658 is compressed tightly against face 688. Having the seam 620 (FIG.37) in compression helps the prevention of debris entry into the seam620.

Visible in FIG. 30 and FIG. 31 are components to engage with the lockingfinger 640. Specifically, there is opening 668 which can receive thedownward portion 648 of the locking finger 640. There is also crossbar676 which fits into gap 646 between the downward portion 648 of thelocking finger 640 and the joint rib 632. Face 658 of the male portion630 is adjacent to face 688 of the female portion 660 when the tire seamis completed.

Male Locking Pin 730.

As will be discussed in detail below, a tire 600 is retained to the rim500 at the joint of the male portion 630 and the female portion 660through the use of two locking pins, a male locking pin 730 and a fingerlocking pin 760. Looking at FIG. 23 and FIG. 28, the route for the malelocking pin 730 (not shown here) may be identified.

The route for insertion of the male locking pin 730 would be:

-   -   through first sidewall bore 734 in the male portion 630 of the        tire 600;    -   through male pin bore 520 in rim 500; and    -   through at least a portion of second sidewall bore 738 in the        male portion 630 of the tire 600.

One of skill in the art will appreciate that the route could start withthe second sidewall bore 738 and end in the first sidewall bore 734unless the tire 600 and male locking pin 730 were designed to force aparticular sequence.

Finger Locking Pin 760.

Looking at FIG. 28 and FIG. 30 and FIG. 25, the route for the fingerlocking pin 760 (not shown here) may be identified.

The route for insertion of the finger locking pin 760 would be:

-   -   through first sidewall bore 764 in the female portion 660 of the        tire 600;    -   through first locking pin bore 524 in rim 500;    -   through finger bore 772 in locking finger 640;    -   through second locking pin bore 528 in rim 500; and    -   through at least a portion of second sidewall bore 768 in the        female portion 660 of the tire 600.

One of skill in the art will appreciate that the route could start withthe second sidewall bore 768 and end in the first sidewall bore 764unless the tire 600 and finger locking pin 760 were designed to force aparticular sequence.

One of skill in the art will appreciate that the joint groove 532 inFIG. 25 could be expanded towards the tip of the finger gap 554 in FIG.25 so that the rim 500 does not include a first locking pin bore 524 anda second locking pin bore 528. Using a rim modified in this way theroute for insertion of the finger locking pin 760 would be:

-   -   through first sidewall bore 764 in the female portion 660 of the        tire 600;    -   through finger bore 772 in locking finger 640; and    -   through at least a portion of second sidewall bore 768 in the        female portion 660 of the tire 600.

While there are advantages to securing the locking finger 640 to the rim500 as shown in the various figures, this may not be essential in alluses, particularly if a male locking pin 740 is engaging the maleportion 630 of the tire segment to the rim 500 close to the seam 620(FIG. 44). Further, an additional locking pin could be placed nearby toengage bores or passageways in the female portion 660 of the seam withthe rim 500 to further stabilize the seam area.

Process of Placing Tire on Rim.

FIG. 32 shows a top-front perspective view of a portion of rim 500 andtire 600. From this view, one can see the female portion 660 seated onthe rim 500.

FIG. 33 shows a front-right-top perspective view of a portion of rim 500and tire 600. In FIG. 33 the male portion 630 of the tire is close tothe female portion 660 but not yet engaged with the locking finger 640in the opening 668.

FIG. 34 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 33 but with the locking finger 640 ofthe male portion 630 beginning to engage with opening 668 in the femaleportion 660.

FIG. 35 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 34 but with the locking finger 640 ofthe male portion 630 almost seated in opening 668 in the female portion660.

FIG. 36 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 35 but with the locking finger 640 ofthe male portion 630 fully seated in opening 668 in the female portion660. Visible in FIG. 36 are male locking pin 730 and finger locking pin760. The male locking pin 730 may have segments with different diameterssuch as first end 744, middle 746, and second end 748. Likewise, thefinger locking pin 760 may have segments with different diameters suchas first end 774, middle 776, and second end 778. It is not requiredthat the male locking pin 730 be interchangeable with finger locking pin760. However, those of skill in the art will recognize that there is anadvantage in reducing the number of unique parts to build and store ininventory.

The locking pins 730 and 760 do not have to be mirror images on eitherside of the longitudinal midline, but one of skill in the art willrecognize that having a pin with two ends that work in the same manneris a slight advantage. Note that the ends 744, 748, 774, and 778 have areduced diameter relative to the middles 746 and 776. This allows an endto be relatively easy to insert into the sidewall bores 734, 738, 764 or768 and then driven with a tool so that the broader middles 746 and 776can be used to expand the relevant bores and make it unlikely that thelocking pins 730 or 760 will come out without a specific effort toremove the pin.

FIG. 37 shows the same front-right-top perspective view of a portion ofrim 500 and tire 600 shown in FIG. 36 but with the male locking pin 730fully inserted into the first sidewall bore 734 and through the secondsidewall bore 738 after passing through the male pin bore 520 in rim 500to hold the male portion 630 to the rim 500. Likewise, the fingerlocking pin 760 is fully inserted:

into the first sidewall bore 764 and

through the second sidewall bore 768 after

passing through the first locking pin bore 524 in rim 500,

the finger bore 772 in locking finger 640, and

the second locking pin bore 528 in rim 500 to lock the locking finger640 and the female portion 660 to the rim 500.

To prevent the locking pins 730 and 760 from coming out in use, thelocking pins 730 and 760 and corresponding holes in the tire 600 and rim500 are designed so the locking pins 730 and 760 have a friction fit andare pressed into the tire 600 and rim 500. The locking pins 730 and 760can have multiple diameters and the holes in the tire and rim could bedesigned to help to lock the locking pins 730 and 760 in place. Forinstance, the bores 520, 524 and 528 in the rim 500 could be 0.125inches in diameter and the middle sections 746 and 776 of the lockingpins 730 and 760 could be slightly smaller than 0.125 inches indiameter, such as 0.124 inches in diameter so that the locking pins 730and 760 do not need to expand rigid rim 500.

The diameter of the locking pins 730 and 760 at the ends 744, 748, 774,and 778 could be noticeably small, such as only 0.100 inches indiameter. But the sidewall bores 734, 738, 764 and 768 could be aboutthis same diameter, 0.100 inches. Since the tire 600 is made of asomewhat flexible material, the 0.124 inch middle diameter for section(746 or 776) of the locking pins 730 and 760 could be pressed with someforce through the 0.100 in diameter of the sidewall bores 734, 738, 764and 768 in the tire 600. Those of skill in the art will appreciate thatthe middle section 766 or 776 would only pass through one sidewall bore734, 738, 764 and 768 in the tire 600 but the locking pin 730 or 760could be inserted from the first side or the second side of the tire600.

Once the locking pin 730 or 760 is fully inserted, the locking pin 730or 760 will tend to stay in position as considerable force would berequired to move the expanded middle section 746 or 776 through any ofthe smaller diameter sidewall bores 734, 738, 764 and 768 in the tire600. This removal of the locking pins 730 or 760 would require directaxial force on the locking pins 730 or 760 and this would not happen byaccident.

While the interaction of the locking pins 730 or 760 with the tire 600and rim 500 as set forth above is desirable, it is not strictlyrequired. Another design that takes advantage of many teachings of thepresent disclosure could have locking pins with constant diameter buthave smaller diameter sidewall bores 734, 738, 764 and 768 in the tire600 to act to hold the pin in place.

Tire Molding.

In FIG. 37 there is a sidewall seam 690 where face 658 of the maleportion 630 is adjacent to face 688 of the female portion 660 of tire600. Note that the tire 600 starting at face 688 of the female portion660 of tire 600 all the way around the rim 500 and back to distal tip694 of locking finger 640 is more than 360 degrees as the locking finger640 extends beyond sidewall seam 690. Molding a tire 600 that is morethan 360 degrees poses some challenges. One solution is to break thetire 600 into two or more segments as described above and haveadditional seams.

FIG. 38 and FIG. 39 illustrate another solution. FIG. 38 is a front viewof rim 500 with specifics on the spacing of the locking grooves 512. Rim500 has nine locking grooves 512 spaced at 41.25 degrees. Theinteractions of the male portion 630 of the tire 600 with the femaleportion 660 of the tire 600 occur in the 30 degrees between the adjacentlocking grooves 512, centered on joint groove 532.

FIG. 39 shows a front view of tire 600 before engagement with the rim500. Notice that the distance from the locking rib 612 which is the lastmale locking rib 696 to the face 658 of the male portion 630 is 15degrees. Likewise, the distance from the locking rib 612 which is thelast female locking rib 698 to the face 688 of the female portion 660 is15 degrees. The locking finger 640 which extends beyond face 658 of themale portion 630 is identified as length A. If length A is 10 degrees,then by spacing the locking ribs 612 in the tire 600 at 40 degreesrather than the rim spacing of locking grooves 512 of 41.25 degrees thenas the tire 600 is applied to the rim 500, each segment of tire 600between adjacent locking grooves 512 of the rim 500 will be stretchedslightly to stretch the locking rib gap of 40 degrees to 41.25 degrees.Eight small stretches of the tire 600 to engage with the rim 500stretches the tire 600 to allow the tire 600 to overlap the lockingfinger 640 with the female portion 660.

Note that much of the small stretch of each segment of tire 600 (1.25/40is a bit more than 3%) will be achieved as the locking rib 612 movesfrom the near edge of the locking groove 512 to the centerline oflocking groove 512. Thus, the user will not need to provide a largestretch of the tire 600 before attempting to engage the locking groove512. One of skill in the art will appreciate that adding additionallocking grooves 512 and locking ribs 612 can be used to increase thenumber of small stretches of the tire 600 and thus increase the totalstretch of the tire 600.

Note that radius 584 in FIG. 38 can be the same as radius 684 in FIG. 39so that the sidewalls of the tire 600 have the same radius as therelevant portion of the rim 500. One could make a tire 600 with a radius684 less than radius 584 if the installation process would tolerateadditional stretching of the tire 600 to fit the rim 500. Having a tire600 with a radius 684 significantly more than radius 584 is analternative to requiring the tire stretch to fit around the rim. Alarger radius 684 could be used to make the length of the arc between698 and 696 larger so opposing faces 658 and 688 will meet without tirestretch when wrapped around the rim with smaller radius 584. Thedownside of this approach is that tire 600 will not grip as tightly tothe rim 500.

Those of skill in the art will appreciate that the specific numbers willvary depending on the angular length of the locking finger 640, thenumber of locking grooves 512 and the desire to stretch the tire. Adesigner may wish to have tire stretch that exceeds the length of thelocking finger 640.

Other Groove/Locking Rib Combinations.

A designer enjoys some latitude in designing a locking groove (compare512) and locking rib (compare 612). To note the range of possiblelocking groove/locking rib combinations FIG. 40, FIG. 41, FIG. 42, andFIG. 43 each show a side view of a partial rim and a partial tire toshow some locking groove/locking rib combinations.

FIG. 40 shows a segment of a rim 804 with segment of a tire 854. Eachtire locking rib 858 fits into a corresponding sized locking groove 808.As the opening 806 of the locking groove 808 is large relative to theleading end 852 of the locking rib 858, the insertion of the locking rib858 into a corresponding sized locking groove 808 is relatively easy butis not effective to stretch the tire 854 or to hold the locking rib 858in the locking groove 808. The choice shown in FIG. 40 may be used whenthe tire 854 is designed for hardness or thickness and not capable ofsignificant stretch during installation.

FIG. 41 shows a segment of a rim 814 with segment of a tire 864. In FIG.41, the locking rib 868 is the same size as the locking groove 818 butthe spacing of locking ribs 868 is smaller than the spacing of thelocking grooves 818 so the tire 864 is stretched during installation.

FIG. 42 shows a segment of a rim 824 with segment of a tire 874. In FIG.42, the locking rib 878 is the same size as the locking groove 828 butthe radially distal end 832 of the locking groove 828 is smaller thanthe radially proximal end 836 of the locking groove. As the leadingsurface 882 of the locking rib 878 is the size of the radially proximalend 836 of the locking groove rather than the smaller radially distalend 832 of the locking groove 828, extra force is required to insert thelocking rib 878 into the locking groove 828 which tends to help lock thelocking rib 878 in the locking groove 828.

FIG. 43 shows a segment of a rim 844 with segment of a tire 894. In FIG.43, the locking rib 898 is the same size as the locking groove 848 butas in the design shown in FIG. 42, extra force will be required to forcethe locking rib 898 through the small opening 846 of the locking groove848.

The selection of locking rib and locking groove is partly dependent onthe operating environment of the tire and both the thickness and thehardness of the tire material. For example, tires in accordance with theteachings of this disclosure have been made from thermoplasticpolyurethane (“TPU”). This class of polymer material is a mix of hardsegments and soft segments. By altering the proportion of hard segmentsto soft segments, one can vary the mechanical properties of the TPU.Thus a design that called for locking ribs to be forced through a narrowopening into the locking groove may benefit from a softer TPU that canallow that temporary change in shape. Likewise, the requirements for thetire portions to stretch between adjacent locking grooves may impact thechoice of TPU used so that the tire is capable of the required stretchwithout making undue demands on the person doing the installation.

Tire Removal.

A tire 600 may be removed from a rim 500 while the rim 500 is stillattached to the shopping cart 110 (See FIG. 15) while optionallyimmobilizing the rim 500 by sticking the distal end of the tool 460through a hole 464 (See FIG. 15) in a portion of the shopping cart 110and a through bore 516 in the rim 500.

FIG. 44 shows that the first step is to remove the locking pins 730 and760. The removal of the locking pins may start with pressing on thelocking pins 730 and 760 on one side of the rim 500 and then pulling onthe locking pins 730 and 760 once they extend out of the tire sidewallon the other side of the rim 500.

FIG. 45 illustrates the insertion of a distal end 594 of a tool 590 suchas an appropriate size flathead screwdriver into the seam 620 (FIG. 44)between the male portion 630 and the female portion 660 of the tire 600.The distal end 594 of the tool 590 may be inserted between the lockingfinger 640 and the first sidewall 604.

FIG. 46 illustrates a continuation of the process as the distal end 594of the tool 590 is moved between the locking finger 640 and the secondsidewall 608. The process may continue for several iterations until thelocking finger 640 is out of the opening 668 in the female portion 660.

Once the locking finger 640 is free of the female portion 660 the maleportion 630 may be peeled back from the rim 500. This process maycontinue around the perimeter of the rim 500 until the tire 600 isentirely free of the rim 500. At this point the rim 500 can beinspected. If the rim 500 is suitable for reuse, then a new tire 600 maybe applied to the rim 500 and locked into place with the locking pins730 and 760 as described above.

ALTERNATIVES AND VARIATIONS

Other Material Choice.

While TPU (thermoplastic polyurethane) has been identified as onepossible material for use with the teachings of the present disclosure,other materials will be readily apparent to one of skill in the artafter considering the cart environment (abrasion, load weights, need toquiet tire movement, et cetera).

Within TPU, a range of material hardness may be obtained. Tires used intesting the teachings of this disclosure have been produced with a ShoreHardness of 85 A. Shore Hardness is sometimes called Shore durometer orsimply durometer. For reference an automotive tire is often in the rangeof 70 A and the wheels of a skateboard are often in the range of 98 A(per Wikipedia at https://en.wikipedia.org/wiki/Shore_durometer.)

The locking pins and the rim may be made from polypropylene. Otherdimensionally stable polymers, metals, or other materials may be used.

More than One Tire Segment.

The example showing tire 600 on rim 500 used one tire segment to coverthe rim 500. The teachings of the present disclosure could beimplemented having two or more tire segments to cover the rim 500. Thereare some advantages for molding in having each tire segment the samelength and each segment having a male portion 630 and a female portion660 but this is not a strict requirement. A rim may be covered by a setof tire segments that are not all the same length. Likewise somesegments may have a pair of male portions 630 and some segments may havea pair of female portions 660.

FIG. 47 shows a tire 900 made from a short segment 910 with a pair ofmale portions 630 with locking fingers 640, one at a first end 914 andone at a second end 918. A corresponding long segment 920 has a pair offemale portions 660 with openings 668 to receive the locking fingers640. The seams may be completed with the use of male locking pins 730and finger locking pins 760 (not shown here) engaging with bores in therim and sidewalls as discussed above. One of skill in the art willappreciate that the rim 500 shown above would need to be modified toaccommodate the change in tire seams from the single seam shown in tire600 with rim 500.

One of skill in the art can appreciate that there may be more than twotire segments but each pair of adjoining segment ends will need to bejoined together and to the rim.

More than One Locking Finger/Female Portion Opening.

The example set forth above had one locking finger 640 that fit into oneopening 668 in the female portion 660 of the tire 600. This is not arequirement to have just one locking finger 640. One of skill in the artcan appreciate, particularly for a wider tire, that it may beappropriate to have more than one locking finger 640 and more than oneopening 668 to receive the locking finger 640. The rim would need to beadjusted to allow a locking pin to engage bores in each locking finger640 to help maintain the seated position of the locking fingers 640.

FIG. 48 is a front-top perspective view of a portion of a tire 930 witha male portion 934 with a pair of locking fingers 640. The tire 930 hasa female portion 938 with a pair of openings 668 to receive the pair oflocking fingers 640. If the use of the pair of locking fingers 640 andpair of openings 668 is because the face of the tire 930 is broader thanthe face of tire 600, then the locking pins would need to be scaled tothe appropriate size. The finger locking pin may engage bores in the rimin three places rather than two places as shown in rim 500. Thus theroute for insertion of the finger locking pin would be:

-   -   through first sidewall bore 764 in the female portion 938 of the        tire 930;    -   through first locking pin bore in rim (not shown);    -   through the first finger bore 772 in first locking finger 640;    -   through middle locking pin bore in rim between the two locking        fingers 640 (not shown);    -   through the second finger bore 772 in second locking finger 640;    -   through final locking pin bore in rim (not shown); and    -   through at least a portion of second sidewall bore 768 (not        visible here) in the female portion 938 of the tire 930.

Those of skill in the art will appreciate that the terms first sidewallbore and second sidewall bore are terms used to describe the travel ofthe locking pin entering from a particular side and the travel of thelocking pin may from the opposite side thus starting with the secondsidewall bore and ending at the first sidewall bore.

Those of skill in the art will appreciate that the concept should beunderstood as including at least one locking finger. There could be morethan two locking fingers, particularly with a wide tire.

Once the concept of a seam with more than one locking finger andcorresponding opening is appreciated, one of skill in the art can seethat a first tire segment end could have at least one locking fingerthat extends outward to a second tire segment end to engage with anopening that receives the locking finger. The first tire segment couldalso have an opening that receives a locking finger extending from thesecond tire segment end. At least one locking pin would capture andretain a portion of the at least one locking finger from the first tiresegment and at least one locking pin would capture and retain a portionof the at least one locking finger from the second tire segment. In thisvariation, it may not be necessary to have a locking pin analogous tothe male locking pin 730 as there would be finger locking pins on bothsides of the seam created connecting the first tire segment end to thesecond tire segment end.

Thus, one can imagine that the segment ends in FIG. 48 could have onelocking finger 640 extending left to right as shown and one lockingfinger 640 extending from right to left (opposite to that shown).

Looking again at the image in FIG. 48, a designer may choose to have atire segment that has a first locking finger 640 extending from left toright on the half of tire segment adjacent to the first sidewall 604 andnot have any locking finger on the half of tire segment adjacent to thesecond sidewall 608 so that there is a face to face joint on that halfof tire seam which is held in place by the actions of the locking pinson each side of the seam. Such a choice is not precluded by theteachings of the present disclosure although in most instances adesigner would prefer a symmetric design that minimizes the length ofseam away from a locking finger 640.

Bores.

The present disclosure shows locking pins that are cylindrical and boresthat are round. While these choices may be the most common, theteachings of the present disclosure do not strictly require roundchoices. A locking pin could have a triangular, square or other shapeand engage with openings in the tire and rim that correspond to theshape of the locking pin. Those of skill in the art will recognize thatnon-round shapes can increase stresses at the corners but this may becompensated for. A designer may choose to place a locking pin of a firstshape in a passageway of a second shape. For example, a round lockingpin could be placed in a passageway that is triangular, square, oroblong providing that the pin can be driven through the passageway.

Locking Finger Could Extend Radially Outward.

The examples discussed in this disclosure show locking fingers thatextend along the circumference of the tire and then substantiallyradially downward into a gap in the rim. This design works well, but adesigner may choose to have a locking finger that extends along a gap inthe center ridge of the rim and then extends upward through acorresponding opening in the female portion of the seam to form theupper surface of the tire. A finger locking pin would engage the lowerportion of the locking finger with the rim and the sidewalls of thefemale portion of the seam. One of skill in the art will appreciate thathaving a locking finger that extends radially outward through an openingin the female portion of the seam will make it expedient to set the maleportion of the seam in place before placing the female portion of theseam on top of the locking finger.

Locking Finger Could Lack a 90 Degree Bend.

The examples discussed in this disclosure show locking fingers thatextend along the circumference of the tire and then substantiallyradially downward into a gap in the rim. This design works well, but adesigner may choose to have a locking finger that extends along a gap inthe center ridge of the rim and does not have a 90 degree bend. A fingerlocking pin would engage a distal portion of the locking finger with therim and the sidewalls of the female portion of the seam. One of skill inthe art will appreciate that having a locking finger that extendslinearly into an opening in the female portion of the seam may requireinsertion of the distal portion of the locking finger into a proximalend of the opening in the female portion before the male portion and thefemale portion are seated upon the rim. The tire segment ends will needto be sufficiently flexible to accommodate this process.

No Limit on Uses for Carts.

While the present disclosure described a particular type of cartwell-known by readers—a shopping cart—there is no intent to limit thescope of the claims to a cart used by someone doing shopping. There aremany carts used for carrying a variety of loads from mail carts to carrymail within a facility to go-karts to allow children to coast down ahill. Any wheel that uses a non-pneumatic tire around a rim couldbenefit from the teachings of the present disclosure. Thus, wheels maybe found in medical, industrial, commercial, residential, academic, orother types of facilities in addition to wheels used on items that areused outdoors.

Other Wheels.

While the most common use of the teachings of the present disclosure arefor wheels on carts, the teachings of the present disclosure may be usedfor wheels that are in a fixed location such as rollers for an assemblybelt or drive wheels that are used in amusement park rides to driveitems such as flume ride cars.

The presently disclosed subject matter is described with specificity tomeet statutory requirements. However, the description itself is notintended to limit the scope of this patent. Rather, the inventors havecontemplated that the claimed subject matter might also be embodied inother ways, to include different steps or elements similar to the onesdescribed in this document, in conjunction with other present or futuretechnologies. Moreover, although the term “step” may be used herein toconnote different aspects of methods employed, the term should not beinterpreted as implying any particular order among or between varioussteps herein disclosed unless and except when the order of individualsteps is explicitly described.

One of skill in the art will recognize that some of the alternativeimplementations set forth above are not universally mutually exclusiveand that in some cases additional implementations can be created thatemploy aspects of two or more of the variations described above.Likewise, the present disclosure is not limited to the specific examplesor particular embodiments provided to promote understanding of thevarious teachings of the present disclosure. Moreover, the scope of theclaims which follow covers the range of variations, modifications, andsubstitutes for the components described herein as would be known tothose of skill in the art.

Where methods and/or events described above indicate certain eventsand/or procedures occurring in a certain order, the ordering of certainevents and/or procedures may be modified. Additionally, certain eventsand/or procedures may be performed concurrently in a parallel processwhen possible, as well as performed sequentially as described above.There was no attempt to exhaustively recite all possible sequencepermutations as the objective was to simply provide enablement of theprocess steps to one of skill in the art.

The legal limitations of the scope of the claimed invention are setforth in the claims that follow and extend to cover their legalequivalents. Those unfamiliar with the legal tests for equivalencyshould consult a person registered to practice before the patentauthority which granted this patent such as the United States Patent andTrademark Office or its counterpart.

What is claimed is:
 1. A method of applying a tire to a rim, the method comprising: forming a tire seam with: a first seam end having at least one locking finger that extends beyond a first seam face, the first seam end having a first seam end first sidewall and a first seam end second sidewall that cover a least a portion of a center ridge that extends along at least a portion of a circumference of the rim; and a second seam end having at least one opening to receive a locking finger behind a second seam face, the second seam end having a second seam end first sidewall and a second seam end second sidewall that cover a least a portion of the center ridge that extends along at least a portion of the circumference of the rim; inserting the at least one locking finger into the at least one opening to draw the first seam face to the second seam face; and after inserting the at least one locking finger into the at least one opening to draw the first seam face to the second seam face, inserting a finger locking pin to engage a passageway in the second seam end first sidewall, a passageway in the second seam end second sidewall, a passageway through a portion of the locking finger, and at least one passageway through the rim.
 2. The method of claim 1 further comprising placing a second locking pin to engage a passageway in the first seam end first sidewall, a passageway in the first seam end second sidewall, and at least one passageway through the rim.
 3. The method of claim 1 wherein inserting the at least one locking finger into the at least one opening to draw the first seam face to the second seam face includes inserting a distal tip of the at least one locking finger radially inward towards a center of the rim through the at least one opening.
 4. The method of claim 1 wherein inserting the at least one locking finger into the at least one opening to draw the first seam face to the second seam face includes inserting a distal tip of the at least one locking finger radially outwards away from a center of the rim through the at least one opening.
 5. The method of claim 1 wherein the first seam end has more than one locking finger that extends beyond the first seam face; the second seam end has more than one opening to receive the more than one locking finger that extends beyond the first seam face; and the finger locking pin engages a passageway through a portion of each of the more than one locking finger.
 6. The method of claim 1 further wherein the second seam end having at least one locking finger that extends beyond the second seam face; and the first seam end having at least one opening to receive a locking finger behind a first seam face; and after inserting the at least one locking finger from the second seam end into the at least one opening in the first seam end, inserting a second finger locking pin to engage a passageway in the first seam end first sidewall, a passageway in the first seam end second sidewall, a passageway through a portion of the locking finger extending from the second seam end, and at least one passageway through the rim.
 7. The method of claim 1 wherein a single tire segment with a single seam covers an entirety of the rim.
 8. The method of claim 1 wherein a set of at least two tire segments with at least two seams covers an entirety of the rim and the set of at least two tire segments are sufficiently similar that a single mold can serially produce the set of at least two tire segments.
 9. The method of claim 1 wherein a set of at least two tire segments with at least two seams covers an entirety of the rim and the set of at least two tire segments are sufficiently different that a single mold cannot serially produce the set at least two tire segments.
 10. A method of applying a tire to a rim, the method comprising: forming a tire seam with: a first seam end having at least one locking finger that extends beyond a first seam face, the first seam end having a first seam end first sidewall and a first seam end second sidewall that cover a least a portion of a center ridge that extends along at least a portion of a circumference of the rim; and a second seam end having at least one opening to receive a locking finger through a second seam face, the second seam end having a second seam end first sidewall and a second seam end second sidewall that cover a least a portion of the center ridge that extends along at least a portion of the circumference of the rim; inserting the at least one locking finger into the at least one opening; and after inserting the at least one locking finger into the at least one opening, inserting a finger locking pin to engage: a passageway in the second seam end first sidewall, a passageway in the second seam end second sidewall, a passageway through a distal portion of the locking finger, and at least one passageway through the rim.
 11. A method for disengaging a seam at a joint between two tire ends for a tire covering a rim, the method comprising: pressing on a first end of a first locking pin at a first tire sidewall to force a second end of the first locking pin to extend outward from a second tire sidewall; removing the first locking pin from engagement with a rim so that a second seam end is no longer engaged with the rim by the first locking pin; and disengaging a locking finger extending from a first seam end from an opening in the second seam end such that the first seam end is disengaged from the second seam end.
 12. The method of claim 11 further comprising: pressing on a first end of a second locking pin at a first tire sidewall on the first seam end to force a second end of the first locking pin to extend outward from a second tire sidewall on the first seam end; and removing the second locking pin from engagement with a rim, such that the first seam end is no longer engaged with the rim by the second locking pin.
 13. The method of claim 11 wherein disengaging the locking finger extending from the first seam end from the opening in the second seam end such that the first seam end is disengaged from the second seam end occurs by pulling the locking finger radially outward from a central axis of the rim.
 14. The method of claim 11 wherein disengaging the locking finger extending from the first seam end from the opening in the second seam end such that the first seam end is disengaged from the second seam end occurs by pulling the opening in a second seam end radially outward from a central axis of the rim.
 15. An assembly comprising a rim with a tire; the rim having a set of locking grooves to receive locking ribs from a tire segment; a tire segment with a first end and a second end, the first end and the second end adapted to form a tire seam; and a spacing of a pair of locking ribs on the tire segment relative to a spacing of a pair of locking grooves on the rim causing a portion of the tire segment to become elongated in order to place a first locking rib in a first locking groove and second locking rib in a second locking groove adjacent to the first locking groove.
 16. A method of applying a tire segment to a rim, the method comprising: placing a tire segment around at least a portion of a rim such that sidewalls of the tire segment cover at least a portion of a center ridge on at least a portion of the portion of the rim; placing at least a portion of a tire joint section of a second type over at least a portion of a tire joint section of a first type to form an overlapped joint; and engaging at least one passageway through the rim so that the overlapping joint is bound to the rim.
 17. The method of claim 16 wherein the step of engaging the at least one passageway through the rim is achieved by placing a locking pin substantially parallel to a central axis of the rim, the locking pin engaging: at least one passageway in the tire joint section of the first type; at least one passageway in the tire joint section of the second type; and at least one passageway in the rim.
 18. The method of claim 16 wherein the step of engaging the at least one passageway through the rim is achieved by: placing a first locking pin substantially parallel to a central axis of the rim, the first locking pin engaging: at least one passageway in the tire joint section of the first type; and at least one passageway in the tire joint section of the second type; and placing a second locking pin substantially parallel to a central axis of the rim, the second locking pin engaging: at least one passageway in the tire joint section of the first type; and at least one passageway in the rim.
 19. The method of claim 16 wherein the step of engaging the at least one passageway through the rim is achieved by: placing a first locking pin substantially parallel to a central axis of the rim, the first locking pin engaging: at least one passageway in the tire joint section of the first type; and at least one passageway in the tire joint section of the second type; and placing a second locking pin substantially parallel to a central axis of the rim, the second locking pin engaging: at least one passageway in the tire joint section of the second type; and at least one passageway in the rim.
 20. The method of claim 16 wherein the step of engaging the at least one passageway through the rim is achieved by extending a pair of half-rivets radially downward towards a center of the rim through passageways in the rim to lock at least a portion of the tire joint section of the second type over at least the portion of the tire joint section of the first type to maintain the overlapped joint.
 21. The method of claim 20 further comprising subsequently removing the tire segment to from the rim by freeing the overlapping joint bound to the rim by cutting off a head of each half-rivet, the head extending out of one of the passageways in the rim. 